New in the pool: underline/strike line styles, super/subscript, caps,
textPosition, links, page breaks, footnotes/endnotes, cell shading and
vertical alignment. normalize() canonicalizes importer-generated note ids and
drops the link mark's default plain:false; FUZZ_SEEDS widens the sweep beyond
the default 50. This is the suite that surfaced the last four export/import
fixes; all 300 sweep seeds now round-trip clean on both legs.